1. Field of the Invention
The present invention relates to a sputtering apparatus, and more particularly, to a sputtering apparatus that effectively provides a plurality of different plasma process recipes inside a single plasma process chamber.
2. Discussion of the Prior Art
As the society has rapidly progressed into an information-oriented society, a demand for flat panel displays having excellent characteristics such as slim profile/size, lightweight, and low power consumption also has increased. Among such flat panel displays, Liquid Crystal Displays (LCDs) have been actively developed because of their superior color reproduction capability.
In general, the LCD is made by a process that includes arranging two substrates to face each other, where each substrate has an electrode formed on an inner surface, and a liquid crystal layer is filled into a gap between the two substrates. An alignment of liquid crystal molecules in the liquid crystal layer changes when a voltage is applied to the electrodes formed on the two substrates. The LCD is enabled to display an image on the screen by varying the light transmittance in accordance with the change in the alignment of the liquid crystal molecules.
The LCD generally has a lower substrate and an upper substrate. The lower substrate is a TFT substrate, which includes a plurality of thin film transistors (TFTs) for applying a signal to a pixel electrode. The TFT is formed by repeating the step of forming and etching metal and insulating layers. The upper substrate is a color filter substrate, which includes a color filter layer having red (R), green (G) and blue (B) color filters arranged in sequential order.
A black matrix layer, which is used for the color filter substrate or an electrode for the TFT substrate, is generally formed by depositing chromium (Cr) by a sputtering apparatus. To form a thin film using sputtering, a target material (a raw material) of the thin film is loaded in a vacuum chamber. A substrate is also disposed at a position corresponding to the target material inside the vacuum chamber. Argon (Ar) ions are supplied into the vacuum chamber to generate plasma. The Ar ions, generated during the formation of the plasma, collide with a surface of the target material, which is negatively charged. Accordingly, target particles emitted from the target material are deposited on the substrate.
A diode sputtering method, a bias sputtering method, an RF sputtering method, a triode sputtering method, a magnetron sputtering method and other suitable sputtering methods are used to form thin films. The magnetron sputtering method, which is widely used, has an advantage of enhancing the thin film deposition rate. The enhancement is achieved by forming the higher density plasma around the target material. Since there is a magnet mounted on a back surface of the target material, more target particles can be emitted.
The sputtering apparatus used in the above described magnetron sputtering methods can be generally classified into an in-line type sputtering apparatus and a cluster type sputtering apparatus.
Compared with the cluster type sputtering apparatus, the in-line type sputtering apparatus enables consecutive sputtering in a local region because a gas is controlled to flow toward a center from a side. Thus, a flow of gas in the in-line type sputtering apparatus shifts in a direction of the substrate transfer. Accordingly, the in-line type sputtering apparatus has a disadvantage in that it is difficult to control the particles and to process in an open process section.
Unlike the in-line type sputtering apparatus, the cluster type sputtering apparatus controls the gas flow from a lower portion toward an upper portion. In the cluster type sputtering apparatus, the target material has an area corresponding to a size of the substrate during the formation of plasma. In addition, plasma is generated gradually depending on the rate of substrate transfer. Thus, the cluster type sputtering apparatus has some advantages, such as easy control of gas flow and small generation of particle source, and has a disadvantage that a plurality of layers cannot be deposited inside a narrow space.
Accordingly, a sputtering apparatus that can deposit a plurality of layers inside a narrow space has been developed that can effectively use a sputtering space by removing a buffer space.